diff --git a/types/office-js-preview/index.d.ts b/types/office-js-preview/index.d.ts
index 9778889180..1d38421847 100644
--- a/types/office-js-preview/index.d.ts
+++ b/types/office-js-preview/index.d.ts
@@ -16912,6 +16912,21 @@ declare namespace Office {
          * `ItemCompose`, `ItemRead`, `MessageCompose`, `MessageRead`, `AppointmentCompose`, `AppointmentRead`
          */
         item: Item & ItemCompose & ItemRead & MessageRead & MessageCompose & AppointmentRead & AppointmentCompose;
+        /**
+         * Gets an object that provides methods to manage the categories master list associated with a mailbox.
+         *
+         * [Api set: Mailbox Preview]
+         *
+         * @remarks
+         *
+         * <table>
+         *   <tr><td>{@link https://docs.microsoft.com/outlook/add-ins/understanding-outlook-add-in-permissions | Minimum permission level}</td><td>ReadMailbox</td></tr>
+         *   <tr><td>{@link https://docs.microsoft.com/outlook/add-ins/#extension-points | Applicable Outlook mode}</td><td>Compose or Read</td></tr>
+         * </table>
+         *
+         * @beta
+         */
+        masterCategories: MasterCategories;
         /**
          * Gets the URL of the REST endpoint for this email account.
          *
@@ -17400,7 +17415,8 @@ declare namespace Office {
      * Represents the categories on an item.
      * 
      * In Outlook, a user can group messages and appointments by using a category to color-code them.
-     * The user defines categories in a master list on their mailbox. They can then apply one or more categories to an item.
+     * The user defines {@link MasterCategories | categories in a master list} on their mailbox.
+     * They can then apply one or more categories to an item.
      *
      * [Api set: Mailbox Preview]
      *
@@ -17555,6 +17571,143 @@ declare namespace Office {
         color: Office.MailboxEnums.CategoryColor;
     }
 
+    /**
+     * Represents the categories master list on the mailbox.
+     * 
+     * In Outlook, a user can group messages and appointments by using a category to color-code them.
+     * The user defines categories in a master list on their mailbox. They can then apply one or more categories to an item.
+     *
+     * [Api set: Mailbox Preview]
+     *
+     * @remarks
+     * <table>
+     *   <tr><td>{@link https://docs.microsoft.com/outlook/add-ins/understanding-outlook-add-in-permissions | Minimum permission level}</td><td>ReadMailbox</td></tr>
+     *   <tr><td>{@link https://docs.microsoft.com/outlook/add-ins/#extension-points | Applicable Outlook mode}</td><td>Compose or Read</td></tr>
+     * </table>
+     * 
+     * @beta
+     */
+    interface MasterCategories {
+        /**
+         * Adds categories to the master list on a mailbox. Each category must have a unique name but multiple categories can use the same color.
+         *
+         * @param categories - The categories to be added to the master list on the mailbox.
+         * @param options - Optional. An object literal that contains one or more of the following properties.
+         *        asyncContext: Developers can provide any object they wish to access in the callback method.
+         * @param callback - Optional. When the method completes, the function passed in the callback parameter is called with a single parameter of 
+         *                 type Office.AsyncResult.
+         *
+         * [Api set: Mailbox Preview]
+         *
+         * @remarks
+         * <table>
+         *   <tr><td>{@link https://docs.microsoft.com/outlook/add-ins/understanding-outlook-add-in-permissions | Minimum permission level}</td><td>ReadWriteMailbox</td></tr>
+         *   <tr><td>{@link https://docs.microsoft.com/outlook/add-ins/#extension-points | Applicable Outlook mode}</td><td>Compose or Read</td></tr>
+         *   <tr><td>Errors</td><td>DuplicateCategory - One of the categories provided is already in the master category list.</td></tr>
+         *   <tr><td></td><td>PermissionDenied - The user does not have permission to perform this action.</td></tr>
+         * </table>
+         * 
+         * @beta
+         */
+        addAsync(categories: CategoryDetails[], options?: Office.AsyncContextOptions, callback?: (asyncResult: Office.AsyncResult<void>) => void): void;
+        /**
+         * Adds categories to the master list on a mailbox. Each category must have a unique name but multiple categories can use the same color.
+         *
+         * @param categories - The categories to be added to the master list on the mailbox.
+         * @param callback - When the method completes, the function passed in the callback parameter is called with a single parameter of 
+         *                 type Office.AsyncResult. If adding categories fails, the asyncResult.error property will contain an error code.
+         *
+         * [Api set: Mailbox Preview]
+         *
+         * @remarks
+         * <table>
+         *   <tr><td>{@link https://docs.microsoft.com/outlook/add-ins/understanding-outlook-add-in-permissions | Minimum permission level}</td><td>ReadWriteMailbox</td></tr>
+         *   <tr><td>{@link https://docs.microsoft.com/outlook/add-ins/#extension-points | Applicable Outlook mode}</td><td>Compose or Read</td></tr>
+         *   <tr><td>Errors</td><td>DuplicateCategory - One of the categories provided is already in the master category list.</td></tr>
+         *   <tr><td></td><td>PermissionDenied - The user does not have permission to perform this action.</td></tr>
+         * </table>
+         * 
+         * @beta
+         */
+        addAsync(categories: CategoryDetails[], callback: (asyncResult: Office.AsyncResult<void>) => void): void;
+        /**
+         * Gets the master list of categories on a mailbox.
+         *
+         * @param options - An object literal that contains one or more of the following properties.
+         *        asyncContext: Developers can provide any object they wish to access in the callback method.
+         * @param callback - When the method completes, the function passed in the callback parameter is called with a single parameter of 
+         *                 type Office.AsyncResult. If adding categories fails, the asyncResult.error property will contain an error code.
+         *
+         * [Api set: Mailbox Preview]
+         *
+         * @remarks
+         * <table>
+         *   <tr><td>{@link https://docs.microsoft.com/outlook/add-ins/understanding-outlook-add-in-permissions | Minimum permission level}</td><td>ReadMailbox</td></tr>
+         *   <tr><td>{@link https://docs.microsoft.com/outlook/add-ins/#extension-points | Applicable Outlook mode}</td><td>Compose or Read</td></tr>
+         * </table>
+         * 
+         * @beta
+         */
+        getAsync(options: Office.AsyncContextOptions, callback: (asyncResult: Office.AsyncResult<CategoryDetails[]>) => void): void;
+        /**
+         * Gets the master list of categories on a mailbox.
+         *
+         * @param callback - When the method completes, the function passed in the callback parameter is called with a single parameter of 
+         *                 type Office.AsyncResult.
+         *
+         * [Api set: Mailbox Preview]
+         *
+         * @remarks
+         * <table>
+         *   <tr><td>{@link https://docs.microsoft.com/outlook/add-ins/understanding-outlook-add-in-permissions | Minimum permission level}</td><td>ReadMailbox</td></tr>
+         *   <tr><td>{@link https://docs.microsoft.com/outlook/add-ins/#extension-points | Applicable Outlook mode}</td><td>Compose or Read</td></tr>
+         * </table>
+         * 
+         * @beta
+         */
+        getAsync(callback: (asyncResult: Office.AsyncResult<CategoryDetails[]>) => void): void;
+        /**
+         * Removes categories from the master list on a mailbox.
+         *
+         * @param categories - The categories to be removed from the master list on the mailbox.
+         * @param options - Optional. An object literal that contains one or more of the following properties.
+         *        asyncContext: Developers can provide any object they wish to access in the callback method.
+         * @param callback - Optional. When the method completes, the function passed in the callback parameter is called with a single parameter of 
+         *                 type Office.AsyncResult. If removing categories fails, the asyncResult.error property will contain an error code.
+         *
+         * [Api set: Mailbox Preview]
+         *
+         * @remarks
+         * <table>
+         *   <tr><td>{@link https://docs.microsoft.com/outlook/add-ins/understanding-outlook-add-in-permissions | Minimum permission level}</td><td>ReadWriteMailbox</td></tr>
+         *   <tr><td>{@link https://docs.microsoft.com/outlook/add-ins/#extension-points | Applicable Outlook mode}</td><td>Compose or Read</td></tr>
+         *   <tr><td>Errors</td><td>PermissionDenied - The user does not have permission to perform this action.</td></tr>
+         * </table>
+         * 
+         * @beta
+         */
+        removeAsync(categories: CategoryDetails[], options?: Office.AsyncContextOptions, callback?: (asyncResult: Office.AsyncResult<void>) => void): void;
+        /**
+         * Removes categories from the master list on a mailbox.
+         *
+         * @param categories - The categories to be removed from the master list on the mailbox.
+         * @param callback - When the method completes, the function passed in the callback parameter is called with a single parameter of 
+         *                 type Office.AsyncResult. If removing categories fails, the asyncResult.error property will contain an error code.
+         *
+         * [Api set: Mailbox Preview]
+         *
+         * @remarks
+         * <table>
+         *   <tr><td>{@link https://docs.microsoft.com/outlook/add-ins/understanding-outlook-add-in-permissions | Minimum permission level}</td><td>ReadWriteMailbox</td></tr>
+         *   <tr><td>{@link https://docs.microsoft.com/outlook/add-ins/#extension-points | Applicable Outlook mode}</td><td>Compose or Read</td></tr>
+         *   <tr><td>Errors</td><td>PermissionDenied - The user does not have permission to perform this action.</td></tr>
+         * </table>
+         * 
+         * @beta
+         */
+        removeAsync(categories: CategoryDetails[], callback: (asyncResult: Office.AsyncResult<void>) => void): void;
+    }
+
     /**
      * Represents a suggested meeting found in an item. Read mode only.
      *